Rubber mix and process of compounding rubber



UNITED; STATES PATENT OFFICE.

ROBERT C. HARTONG, OF AKRON, OHIO, ASSIGNOR TO THE GOODYEAR TIRE & RUBBER COMPANY, OF AKRON, OHIO, A CORPORATION OF OHIO.

RUBBER MIX AND PROCESS OF COMPOUNDING- RUBBER.

Specification of Letters Patent.

Patented Mar. 8, 1921.

No Drawing. Original application filed March 30, 1917, Serial No. 158,525. Divided and this application filed. January 80, 1919. Serial No. 274,017.

T all whom it may concern:

Be it known that 1, ROBERT C. HARTONG, a citizen of the United States, residin at Akron, in the county of Summit and tate stood from the following specification.

In the manufacture of rubber products a large variety of compounding ingredients are employed and in every instance it is desirable to secure a uniform and homogeneous mixture of these ingredients, both with one another and with the rubber, in order that the vulcanized product may be of highest quality. My invention is particularly concerned with a-method of procedure by which compounding ingredients may be incorporated into and disseminated through the rub} ber mix in the finest practical state of subdivision and in such a manner as to secure true homogeneity. This end I find to be best attained by the use of a liquid carrier for the compounding ingredients.

It is a well understood fact that-the action of a solvent liquid upon a solid is. to disintegrate that solid and break it up lnto excessively small particles, these particles when dispersed through the liquid being said to dissolve therein. For example it is believed that some substances of which the soluble carbohydrate sugar may be taken as an illustration, disintegrate into their ultimate molecules in the presence of a sufficiently large volume of water, so that in a sugar solution the sugar exists in the most extreme state of physical subdivision or dis persion of which it is capable. Other substances, such as glue for instance, when dissolved in water do not appear to be subdivided to the same extent as the sugar particles mentioned, but on the other. hand they enter into some species of combination with the water by which they become enormously swollen or distended and if subiected to a grinding action in this distended cond1t1on may be more finely divided than is possible in handling the dry product. In still other instances there may be a disintegratlng actlon by the solvent not approaching the disintegrating action effected 1n the case of the decreasing the rate of association of the articles of a finely divided substance. hus for example when coarse materials of the nature of barytes are suspended in water, each individual particle is retained in its separate state, agglomeration of the particles being prevented so long as the water'is present in reasonable amounts.

It is therefore true that a carrier liquid is in general useful to some extent, either in effecting disintegration of a solid substance or preventing or retarding the'reassociation of disintegrated particleswhich have been "reduced to a fine state of subdivision by any means.'- From this standpoint alone therefore the use of a carrier liquid is advantageous inthe compounding of rubber. A

further important advantage arises from the fact that the liquid carrying the solid with it may be disseminated through the rubber with a relatively small amount of mechanical working, thereby avoiding the breaking down and loss of tensile strength of the rubber which results from the excessive work ing sometimes necessarily resorted to in order to effect thorough dissemination of a solid compounding ingredient. The carrier.

of the carrier liquid the difliculty of efiecting thorough dissemination of these relatively small percentages through the mass of the rubber mix is substantially lessened.

I have found that for the majority of compounding materials employed in the manufacture of rubber, water forms the most desirable carrier liquid, both because of its cheapness and because of the fact that it does not act upon the rubber in the mix. It must be understood, however, that other carrier liquids may be employed without departure from the basic principles of my invention.

After the mix has been satisfactorily compounded the water or other carrier liquid must be removed, it being well known that any large percentage of vaporizable matter such as Water in the ordinary rubber mix is highly disadvantageous in that vapors areevolved during vulcanization and the vulcanized product is thereby rendered porous. I find that the water may readily be removed, however, either by vacuum drying or by the use of a current of air or other inert gas, the expense of the treatment being far outweighed by the advantages resulting from the use of the carrier liquid in compounding.

In the use of alumina as a compounding ingredient by ordinary methods employed for its dissemination through the mass it is difiicult to secure satisfactory results. If, however, the alumina be suspended in water in the form of the hydrate (Al(OH) which may readily be produced in the vehicle by precipitation or other means well known in the chemical arts, this hydrate assumes a more or less colloidal state and is in a much finer state of subdivision or dispersion than any to which the oxid it self may be reduced. By incorporation'of such an aqueous suspenslon of aluminum hydroxid in a rubber mix, I secure a perscribed, but may be utilized for the incorcolloidal solutions of gelatin or other'pre" cipitative colloids and are added to the rubber, moisture being subsequently removed, they are homogeneously incorporated in an exceedingly 'fine state of dispersion and a very decided improvement in the quality of the finished product is secured.

It will be understood that my invention is not dependent upon the soundness of the theories which have been stated in the present application nor is it limited to the specific materials or methods of manipulation named, excepting so far as such limitations are included within the terms of the accompanying claims.

This application is a division of my prion application Serial No. 158,525, filed March 30, 1917.v

I claim:

1. The process of compounding rubber which consists in adding to rubber, water carrying in suspension hydroxid of aluminum, mixing the water and aluminum h vdroxid with the rubber, driving off the water, and heating the mix with a vulcanizing agent to effect vulcanization.

2. A rubber mix containing rubber and aluminum hydroxid in finely dispersed form homogeneously distributed therethrough.

In witnesses whereof, I have hereunto. signed my name in the presence of two sub scribing witnesses.

ROBERT C. HARTONG.

Witnesses:

L. M. HARTMAN, B. J. MCDANEL. 

